1. Technical Field
The present invention relates to an inkjet printer and to a control method for an inkjet printer that executes a cleaning process to discharge ink droplets from the nozzles of plural inkjet heads that are carried on a head carriage in order to prevent the plural nozzles of the inkjet head from clogging.
2. Related Art
The nozzles of an inkjet head used in an inkjet printer can become clogged as a result of an increase in the viscosity of ink left inside the nozzles, resulting in the clogged nozzles being unable to discharge a sufficient volume of ink. If printing is attempted using an inkjet head in which some nozzles are clogged, dots may be dropped or poorly formed and print quality drops accordingly. Inkjet printers therefore regularly or at specified times move the carriage that carries the inkjet head to a home position removed from the printing area so that the nozzle surface of the inkjet head is opposite a head cap with an ink sponge used for maintenance, and then discharge a specific amount of ink from each of the nozzles to flush (clean) the nozzles.
Japanese Unexamined Patent Appl. Pub. JP-A-H10-146993 teaches a flushing control method for an inkjet printer. The flushing control method taught in JP-A-H10-146993 counts how long (the time) the maintenance head cap caps the inkjet head while the carriage is stopped in the home position, and flushes the nozzles regularly based on the elapsed time.
In the case of such an inkjet printer with plural inkjet heads, the printer also has the same number of maintenance head caps as inkjet heads. An ink sponge and a suction mechanism for vacuuming ink from each of the nozzles is disposed for each of the maintenance head caps. The suction mechanism therefore requires more suction channels than when there is only one maintenance head cap, and size and cost both increase because a motor with a strong suction force must be provided.
A single maintenance head cap that can cap the nozzle surface of one inkjet head at a time could conceivably be used, and the inkjet heads could be sequentially positioned opposite the maintenance head cap for flushing or other head maintenance operation. If the inkjet heads are not flushed in the appropriate order before printing starts in this configuration, wasted motion is created in the movement of the head carriage. More specifically, the start of printing will be delayed if the inkjet head is not appropriately flushed before printing starts, and printer throughput will drop.